The genus Piper distributed mainly in tropical
regions of the world. Several species have great economic and cultural
importance including P. nigrum, P. betle, P. methysticum,
etc. Many species have been used for foods, medicines, stimulants,
antiseptics and antioxidants in Thai culture [1].

Our taxonomic accounts on this genus are based on the
stamen and stigma numbers and characters, floral bract morphology, leaf
shape, and leaf venation [2].

Discovered Piper species in Thailand

We have explored the genus since 1999. Until July 2009,
43 species were reported in the second edition of The genus Piper
in Thailand.
However the international publication [2] included only 40 species. The
three addition species that the reviewers asked to omit are P.
brevicaule, P. crocatum and P. umbellatum.

The reasons, from the reviewers, of omitting are:

- P. brevicaule is synonymous of P.
sarmentosum which further checking is needed.

- P. crocatum and P. umbellatum
are introduced.

P.
crocatum
is actually introduced, however people can easily see in plant markets and
in QueenSirikitBotanic Garden,
Chiang Mai. Therefore, it is useful for reader to include this species in
the book. Additionally, we have discovered P. umbellatum in natural
wilds in many places of Thailand
including National Parks and Wildlife Sanctuaries [1]. So we included it in
the book.